Could physics help to avoid disasters like the Love Parade tragedy?

As Germany is mourning the death of the victims of the Love Parade mass panic, new strategies to evacuate events will be ever more important in the future.

Andreas Schadschneider, a professor of theoretical physics at Cologne University, tells July’s Physics World readers about a new project that will model people as particles to make evacuation safer.Professor Schadschneider talks about his involvement in Hermes, a new German government-funded project, which aims to protect and save lives by developing an “evacuation assistant”.

Professor Schadschneider is a researcher of crowd dynamics – how people move in large groups. This insight underpins the evacuation assistant’s computer software – the electronic brains of the operation. Combined with information from CCTV cameras, smoke detectors, ticket sales and the building plan, the software could allow stadiums and similar venues to be cleared faster and more safely than is possible now.

To study crowd dynamics, physicists borrow theories from physics that describe how large groups of particles move. An individual person is treated like, for example, a single air or water molecule.

As for particles, two different theories are used to model crowd dynamics. The first takes the approach that we will know what will happen if we know all the forces. (It is “deterministic”.) A particle’s repulsive force when close to another particle is analogous to a person’s need for personal space and the tendency to not get too close to others.

The second model looks at the probability of people’s decisions. (It is “stochastic”.) Since one person may make a different choice to someone else in the exact same situation, or may behave differently themselves depending on their mood, assigning a probability reflects this uncertainty.

The so-called floor-field model takes the stochastic approach one step further by assuming that pedestrians leave a trace or footprint that others have a tendency to follow subconsciously – sort of like ants following a chemical trail, but for humans it is psychological.

The Hermes evacuation assistant will use a combination of both models, and once developed, the system will not only provide data on the distribution of people in a venue and the availability of escape routes, but will also predict how they will leave. It can then provide information in real time to stadium managers who can take appropriate action to ensure that the crowd leaves as quickly and safely as possible.

As Schadschneider explains, “What makes our project so unique is the close co-operation between experimentalists and modellers, and the physics perspective that allows us to identify analogies with physical theories that can be built on and adapted.

“So next time you leave a stadium, or any large and crowded building, rather than dwelling on defeat you could take a moment to imagine yourself as not a person but a particle.”

Also in the July edition:

• When atomic physicist Josh Silver thought of a new technology that could help billions of people in the developing world, he just had to pursue it. Louise Mayor tells the story of Silver’s invention of spectacles that can be self-adjusted to the user’s prescription
• Following headlines hailing the “first synthetic cell”, Richard Jones, a professor of physics at the University of Sheffield, questions just how far we have got towards creating life from scratch
• Research carried out more than 20 years ago in radio astronomy has led to a transformation in how we use the Internet. Radioastronomer John O’Sullivan explains how he and his research team invented the technology behind Wi-Fi